November 21, 2012

TOUGHEN UP, BUTTERCUP:

The team assessed the effects of different personality traits on the degree of pain relief provided by a placebo. Volunteers were told they were going to experience pain from a continuous injection of hypertonic salt water into their jaw muscle, but that a 'pain killer' (disguised placebo) would be applied beforehand.

The researchers measured levels of the stress hormone cortisol in the blood before and after the test to evaluate levels of stress experienced by the participants, as well as evaluating the degree of secretion and activation of pain killing opioid chemicals in the brain during the experiment.

They found that people who scored highly for personality traits such as altruism, straightforwardness, and resiliency on psychiatric questionnaires had the greatest pain relief after placebo treatment, the lowest levels of cortisol in the blood, and the greatest degree of opioid activation in the brain.

In contrast, people who scored highly for being angry or hostile did not feel pain relief in response to placebo, had higher levels of cortisol, and had the lowest measurable amount of opioid activation.

"We ended up finding that the greatest influence came from a series of factors related to individual resiliency, the capacity to withstand and overcome stressors and difficult situations," said Zubieta.

"People with those factors had the greatest ability to take environmental information - the placebo - and convert it to a change in biology."

"This is a really interesting study that shows that placebo analgesia is associated with certain positive psychological traits," said neuro-rheumatologist and pain expert Anthony Jones from the University of Manchester in England.

"The nice thing about this study is that they have shown that the strength of these relationships is related to the release of natural opiates in regions of the brain that are concerned with emotional regulation and resilience to stress and change," he added.

Zubieta and colleagues said that people who are able to manufacture these 'natural pain killers' in response to placebo may be more resilient in stressful situations, which is supported by the lower levels of cortisol seen in these individuals.

They may also make better patients and have a better patient-doctor relationship than people who are naturally more hostile.

"Placebo effects are not necessarily due to placebo pills," commented Colloca.